Alternating pressure pads are well known for the prevention and management of decubitus ulcers in bedridden patients. The formation of decubitus ulcers, commonly known as bedsores, results from, amongst other things, the pressure applied to certain portions of the skin of a bedridden patient.
Alternating pressure pads generally comprise two sets of alternately inflatable cells. A high air pressure in the pads may be needed to support the bony protuberances of a patient and to ensure that the patient is lifted sufficiently away from deflated cells of the pad so that adequate pressure relief is provided. A low air pressure, however, is desirable since it provides a pad which is softer and more comfortable. Optimal pressure support therefore not only varies from patient to patient but also during a given inflation cycle of the pad, since the pressure supporting points will change during a cycle.
The required optimal support pressure will vary even more as a patient changes from a supine to a sitting position when the bed frame is profiled to raise the head of the patient as the weight of the patient becomes more concentrated on the part of the support under the buttocks. There is a greater risk of the patient “bottoming” with the support surface contacting the surface of the bed thereby reducing the pressure relief. Bottoming can be a particular problem if the backrest is used to position the patient in a more upright or profiled position as their weight is not as evenly distributed. This applies equally to an alternating pressure pad as well as a static pressure pad.
It is known to provide a pressure controller to set an optimal pad support pressure. This may be a regulator for the compressor supplying air or a microprocessor controlling the output of the compressor to the pressure pad.
It is known to have rotational sensors in some bed frames on which the mattress is located which can derive the angle of the bed frame and therefore the mattress, and this information is then used by the pump unit to increase the mattress pressures. This however limits the sensors to only work when a mattress is connected to an expensive integrated mattress-bed frame system, and the cost of the electronics and feedback control system is likely to be very expensive. There are also commercially available incline sensors that use electronic transducers mounted on a circuit board placed in the head section of the mattress with circuitry back to the pump unit. These sensors are undesirable from a cost perspective due to the expense of the electronic board and ancillary hardware needed to read the information and then control the cells pressures. They are even more undesirable from a safety perspective as there are electronics close to the patient in an environment where fluid could well be present. There are also implications for the cleaning of the mattress with the electronics needing to be removed first.